Please help me with the problem below.
Find the volume of a tetrahedron with vertices: $O(0,0,0)$, $A(1,2,3)$, $B(-2,1,5)$, $C(3,7,1)$ by using triple integral.
Hint: First find the the equations of the planes.
Note: My professor told me that I can use change of variables (which I need to calculate the Jacobian and then the volume of a "simpler" tetrahedron).